Resonant DC-DC Converter Phase-Shift Control for Wide-Range ZVS
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Immittance resonant converters face challenges in controlling output power and current across wide voltage and power ranges, particularly at light load conditions, leading to increased conduction and switching losses due to fixed frequency control methods.
Innovation Solution
A phase-shift based modulation strategy is implemented using three-level switching of inverter and rectifier bridges to achieve zero-voltage-switching (ZVS) and near zero-current-switching (ZCS) of semiconductor devices, allowing for simultaneous regulation of output power and current, reducing switching and conduction losses across the entire load range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If fixed frequency control methods are used in immittance resonant converters, then the converter can operate at a stable switching frequency, but conduction losses and switching losses increase significantly at light load conditions
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The control system dynamically adjusts the switching frequency based on the load condition and desired output voltage, allowing the converter to operate efficiently across a wide range of power levels from full load down to approximately 5% of rated power while maintaining optimal loss characteristics at each operating point
Solution Approach 2:
The patent changes the switching frequency parameter adaptively to optimize converter performance. By varying the switching frequency in response to changing load conditions and output voltage requirements, the converter achieves both wide adaptability across voltage and power ranges and minimal energy losses at all operating points including light load conditions
2Loss of energy
If soft-switching is enabled to reduce switching losses, then switching efficiency improves, but the circuit design becomes more complex
Solution Approach 1:
The patent employs resonant oscillation in the LC tank circuit to create soft-switching conditions. By operating at or near the resonant frequency of the tank circuit, the converter achieves zero-voltage-switching (ZVS) and near zero-current-switching (ZCS) of semiconductor devices, dramatically reducing switching losses without requiring complex additional soft-switching circuitry
Solution Approach 2:
The patent achieves multiple functions with a unified approach: the resonant LC tank circuit simultaneously provides voltage transformation, current regulation, and soft-switching capability. The phase-shift modulation between full-bridge inverters on either side of the tank circuit enables both power transfer control and loss reduction, eliminating the need for separate complex soft-switching circuits
3Power
If phase-shift modulation is used to control output power, then power regulation is achieved, but voltage-current overlap losses increase during turn-off
Solution Approach 1:
The patent uses periodic phase-shift modulation between the full-bridge inverters to control output power. By varying the phase difference between the two inverters in a periodic manner synchronized with the resonant frequency, the converter achieves smooth power regulation while the resonant tank circuit naturally manages the voltage-current overlap to minimize losses during switching transitions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly minimizes converter losses, including at light load conditions, enabling efficient operation over a wide range of output voltage and power, while maintaining zero-voltage-switching of all devices.
Implementation Method 1
a resonant network, the circuit electrically connected to the inverter output terminal; wherein the switching frequency of the converter is equal to the resonant frequency
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
A novel phase-shift based modulation strategy is disclosed that enables a DC-DC converter (100) to operate with zero-voltage-switching (ZVS) across wide voltage and power range. The converter (100) operates at a fixed fundamental frequency, with the output current controlled based on an amount of phase shift of the fundamental component at the output of an inverter portion (110) of the converter (100). To achieve soft switching, a rectifier portion (130) of the converter (100) is controlled to phase shift the fundamental component of the rectifier voltage observed at a rectifier reference terminal (131). More specifically, by requiring a phase shift of the voltage at the rectifier reference terminal (131) relative to the output voltage of the inverter (110), the inverter current is such that ZVS is achieved. A converter (100) and method are provided to implement DC-DC conversion with soft switching.